Various methods for opening a fiber bundle, particularly a bundle of crimped fibers for use in a brush part or the like of a cleaning member have been being considered.
For example, PTL 1 describes a method for opening continuous filaments, the method including transporting crimped tow by means of a plurality of rolls; and applying a resistance on at least one side of the tow by slidingly contacting at least one sliding body onto the tow at between rolls, whereby continuous filaments stacked in a thickness direction of the tow are caused to sift in a transporting direction of the tow to open the tow and to spread the continuous filaments in a width direction of the tow.
PTL 2 describes an apparatus which opens tow so that the opened tow has an almost flat cross section, the apparatus including a device for widening the tow by blowing air onto the tow passing through a cylindrical chamber, a mechanism for opening the tow by running the tow through upstream nip rolls disposed and then downstream nip rolls to tighten the tow, and a device for thickening the tow by blowing air into the tow passing through a cylindrical chamber. Such apparatus includes a plurality of the widening devices, at least one of which is configured to act on the tow between the upstream nip rolls and the downstream nip rolls.